Endoscopic bite block

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase of PCT Application No. PCT/IL05/001291, filed on Dec. 1, 2005, the disclosure of which is incorporated herein by reference

REFERENCE TO RELATED APPLICATIONS

Reference is made to PCT Patent Application PCT/IL2004/000430, filed May 20, 2004, entitled “ENDOSCOPIC BITE BLOCK”, the disclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of bite blocks for endoscopic use and specifically to endoscopic bite blocks suitable for use with gas sampling or delivery cannulae.

BACKGROUND OF THE INVENTION

The following U.S. Patents are believed to represent the current state of the art: U.S. Pat. Nos. 5,174,284; 6,257,238; 6,422,240; 5,273,032 and 5,513,634.

SUMMARY OF THE INVENTION

The present invention seeks to provide a new endoscopic bite block.

There is thus provided in accordance with a preferred embodiment of the present invention a bite block assembly adapted for capnography and oxygen delivery to a subject, the bite block assembly including a first capnography passageway adapted for passage therethrough of exhaled breath from the subject to a capnograph, and a second oxygen delivery passageway, separate from the first passageway, adapted for passage therethrough of oxygen from an oxygen source to the mouth of the subject.

Preferably the bite block assembly also includes a gas collection cannula having formed therein the first capnography passageway. Additionally the gas collection cannula also includes an oxygen delivery cannula adapted to deliver oxygen from the oxygen source to the nostrils of the subject. More preferably the oxygen delivery cannula is connected to the oxygen source by a gas delivery tube.

Preferably the bite block assembly also includes a bite block having formed therein the second oxygen delivery passageway.

More preferably the bite block assembly also includes a tube element adapted to connect the oxygen delivery cannula to the second oxygen delivery passageway. Additionally, the tube element includes a branch of the gas delivery tube, and is adapted to connect to the second oxygen delivery passageway. Additionally the tube element is sealed by a normally closed valve. Preferably the normally closed valve includes a luer valve. Additionally a mating luer portion of the luer valve is mounted onto the oxygen delivery passageway.

Preferably the tube element is permanently mounted onto the bite block and is adapted to connect to the gas delivery tube at a connection point formed therein. Additionally the connection point is sealed by a normally closed valve. Preferably the normally closed valve includes a luer valve. More preferably a mating luer portion of the luer valve is mounted onto the tube element.

There is thus provided in accordance with another preferred embodiment of the present invention, a capnography system including a capnograph, a bite block adapted to maintain the mouth of a subject open during a medical procedure, an exhaled breath sampling element which is connectable to the capnograph and mountable onto the bite block, and an oral oxygen delivery passageway which is connectable to the bite block for delivering oxygen from an oxygen source to the mouth of the subject.

Preferably the exhaled breath-sampling element has at least one gas collection passageway, formed therein, the gas collection passageway being configured to collect exhaled breath of the subject. Additionally the at least one gas collection passageway includes a nasal gas collection passageway configured for collecting breath exhaled through at least one nostril of the subject. Additionally or alternatively the at least one gas collection passageway includes an oral gas collection passageway configured for collecting breath exhaled through the mouth of the subject.

Preferably the capnography system also includes a nasal gas delivery passageway for delivering oxygen from the oxygen source to at least one nostril of the subject. Additionally the nasal gas delivery passageway is connected to the oxygen source by a gas delivery tube. More preferably the oral oxygen delivery passageway includes a tubular branch of the gas delivery tube.

Preferably the oral oxygen delivery passageway is sealed by a normally closed valve. Additionally the normally closed valve includes a luer valve. More preferably a mating luer portion of the luer valve is mounted onto the oral oxygen delivery passageway.

Preferably the oral oxygen delivery passageway is permanently mounted onto the bite block and is adapted to connect to the gas delivery tube at a connection point formed therein. Additionally the connection point is sealed by a normally closed valve. More preferably the normally closed valve includes a luer valve. Additionally a mating luer portion of the luer valve is mounted onto the oral oxygen delivery passageway.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> are simplified pictorial illustrations of an oral nasal sampling cannula forming part of an endoscopic bite block assembly, constructed and operative in accordance with a preferred embodiment of the present invention, in retracted and extended orientations respectively;

<figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref> are front-view and rear-view simplified pictorial illustrations of an endoscopic bite block forming part of an endoscopic bite block assembly, constructed and operative in accordance with a preferred embodiment of the present invention;

<figref idrefs="DRAWINGS">FIG. 3</figref> is a simplified sectional pictorial illustration of the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref>, taken along sections lines III-III in <figref idrefs="DRAWINGS">FIG. 2B</figref>;

<figref idrefs="DRAWINGS">FIG. 4</figref> is a simplified schematic illustration of the connection between the oral nasal cannula of <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> and the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 2A-3</figref>;

<figref idrefs="DRAWINGS">FIGS. 5A</figref>, <b>5</b>B, <b>5</b>C, <b>5</b>D, <b>5</b>E, <b>5</b>F and <b>5</b>G are pictorial illustrations of various stages of typical use of the endoscopic bite block assembly of <figref idrefs="DRAWINGS">FIGS. 1A-4</figref>;

<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref> are simplified pictorial illustrations of an oral nasal cannula forming part of an endoscopic bite block assembly, constructed and operative in accordance with another preferred embodiment of the present invention, in retracted and extended orientations respectively;

<figref idrefs="DRAWINGS">FIGS. 7A and 7B</figref> are front-view and rear-view simplified pictorial illustrations of an endoscopic bite block forming part of an endoscopic bite block assembly, constructed and operative in accordance with another preferred embodiment of the present invention;

<figref idrefs="DRAWINGS">FIG. 8</figref> is a simplified sectional pictorial illustration of the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 7A and 7B</figref>, taken along sections lines VIII-VIII in <figref idrefs="DRAWINGS">FIG. 7B</figref>;

<figref idrefs="DRAWINGS">FIG. 9</figref> is a simplified schematic illustration of the connection between the oral nasal cannula of <figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref> and the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 7A-8</figref>;

<figref idrefs="DRAWINGS">FIGS. 10A</figref>, <b>10</b>B, <b>10</b>C, <b>10</b>D, <b>10</b>E, <b>10</b>F and <b>10</b>G are pictorial illustrations of various stages of typical use of the endoscopic bite block assembly of <figref idrefs="DRAWINGS">FIGS. 5A-9</figref>;

<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref> are simplified pictorial illustrations of an oral nasal cannula forming part of an endoscopic bite block assembly, constructed and operative in accordance with yet another preferred embodiment of the present invention, in retracted and extended orientations respectively;

<figref idrefs="DRAWINGS">FIGS. 12A and 12B</figref> are front-view and rear-view simplified pictorial illustrations of an endoscopic bite block forming part of an endoscopic bite block assembly, constructed and operative in accordance with yet another preferred embodiment of the present invention;

<figref idrefs="DRAWINGS">FIG. 13</figref> is a simplified sectional pictorial illustration of the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 12A and 12B</figref>, taken along sections lines XIII-XIII in <figref idrefs="DRAWINGS">FIG. 12B</figref>;

<figref idrefs="DRAWINGS">FIG. 14</figref> is a simplified schematic illustration of the connection between the oral nasal cannula of <figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref> and the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 12A-13</figref>; and

<figref idrefs="DRAWINGS">FIGS. 15A</figref>, <b>15</b>B, <b>15</b>C, <b>15</b>D, <b>15</b>E, <b>15</b>F and <b>15</b>G are pictorial illustrations of various stages of typical use of the endoscopic bite block assembly of <figref idrefs="DRAWINGS">FIGS. 11A-14</figref>.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A bite block is a device commonly used during upper gastro-intestinal endoscopic procedures to facilitate passage of an esophago-gastro-duodenoscopy (EGD) endoscope. The purpose of the bite block is to allow the physician to perform the procedure without the subject interfering by biting and damaging the endoscope tubing inserted via his mouth, whether voluntarily or involuntarily.

The upper gastro-intestinal endoscopic procedure itself, together with the use of a bite block, is often highly uncomfortable for the subject and therefore it is very common for the subject to be sedated during the procedure. Despite this, it is common for the subject to show opposition to the procedure.

During upper gastro-intestinal endoscopy, and especially during long duration procedures performed under sedation, CO2 monitoring is often performed using a separate nasal or oral/nasal cannula in conjunction with a bite block. Concomitant use of bite blocks and cannulae may noticeably affect capnographic performance for a number of reasons, including inter alia misalignment between the cannula and the bite block and inefficient oral sampling due to the space taken up by the endoscope. The present invention provides a solution that generally does not affect the capnographic performance.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>, which are simplified pictorial illustrations of an oral nasal sampling cannula forming part of an endoscopic bite block assembly, constructed and operative in accordance with a preferred embodiment of the present invention, in retracted and extended orientations respectively.

<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> show an oral nasal sampling cannula <b>10</b>, which is adapted for collection of gases, such as carbon dioxide, exhaled by a subject, and for supplying oxygen to the subject.

The oral nasal sampling cannula <b>10</b> comprises a main body portion <b>12</b>, having formed therein an exhaled breath collection bore <b>14</b> and an oxygen delivery bore <b>16</b>. A pair of hollow nasal prongs <b>18</b>, which are adapted for insertion into the nostrils of the subject, is integrally formed with the main body portion <b>12</b>. A hollow oral prong <b>22</b>, which is formed with a limiting rib <b>23</b> and a cut-away tip <b>24</b>, is mounted onto a bottom surface of main body portion <b>12</b>. An oral breath directing element <b>26</b>, which is preferably in the shape of a cut-away tube, is slidably mounted onto oral prong <b>22</b> by a mounting portion <b>28</b>, and positioning of the oral breath directing element <b>26</b> is limited by the limiting rib <b>23</b> of oral prong <b>22</b>.

A channel formed in oral prong <b>22</b> is in fluid flow connection with channels formed in nasal prongs <b>18</b>, thereby forming a single junction <b>32</b>. Single junction <b>32</b> is in fluid flow communication with exhaled breath collection bore <b>14</b>, which in turn is in fluid flow communication with an exhaled breath collection tube <b>34</b>, which is adapted to be connected to a breath test analyzer or a capnograph (not shown), such as Microcap® which is commercially available from Oridion Medical LTD. of Jerusalem, Israel.

Main body portion <b>12</b> is formed with oxygen delivery openings <b>36</b>, which are in fluid flow communication with oxygen delivery bore <b>16</b>, which in turn is in fluid flow communication with an oxygen delivery tube <b>38</b>. Alternatively, at least one nasal oxygen delivery prong, adapted for insertion into the subject's nostril, may be used instead of oxygen delivery openings <b>36</b>. Oxygen delivery tube <b>38</b> is adapted to be connected to a source of oxygen (not shown).

Oxygen delivery tube <b>38</b> and exhaled breath collection tube <b>34</b> may optionally be placed around the ears of the subject, thereby stabilizing the oral nasal sampling cannula <b>10</b> on the subject's face, such that any movement of the subject will have a negligible effect on the placement of the oral nasal sampling cannula <b>10</b>.

It is appreciated that oral breath directing element <b>26</b> may be in a retracted orientation as shown in <figref idrefs="DRAWINGS">FIG. 1A</figref>, or in an extended orientation as shown in <figref idrefs="DRAWINGS">FIG. 1B</figref>, thereby allowing the oral nasal sampling cannula <b>10</b> to be suited to the facial dimensions of the subject, resulting in more efficient collection of exhaled breath.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref>, which are front-view and rear-view simplified pictorial illustrations of an endoscopic bite block forming part of an endoscopic bite block assembly constructed and operative in accordance with a preferred embodiment of the present invention and to <figref idrefs="DRAWINGS">FIG. 3</figref>, which is a simplified sectional pictorial illustration thereof.

<figref idrefs="DRAWINGS">FIGS. 2A</figref>, <b>2</b>B and <b>3</b> show an endoscopic bite block <b>50</b>, which is adapted to be inserted into the mouth of a subject while the subject is sedated, to ensure that the mouth of the subject is maintained open during the endoscopy process and that the subject does not interfere with the process by biting on the medical instruments used.

The endoscopic bite block <b>50</b> includes a main body portion <b>52</b>, having formed therein a central opening <b>54</b>. A hollow tubular portion <b>56</b> extends distally from main body portion <b>52</b>, such that the opening of tubular portion <b>56</b> is an extension of central opening <b>54</b>. Central opening <b>54</b> is of a first height, indicated by H<b>1</b> in <figref idrefs="DRAWINGS">FIG. 3</figref>, which is typically 16 to 20 mm in bite blocks for adult use, which is the height required by medical personnel for performing an endoscopy. In order to ensure that during breath sampling, oral prong <b>22</b> of oral nasal sampling cannula <b>10</b> (<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) does not interfere with the space required by medical personnel for performing the endoscopy procedure, the height of tubular portion <b>56</b> is greater than the height H<b>1</b> of the central opening <b>54</b> as indicated by H<b>2</b> in <figref idrefs="DRAWINGS">FIG. 3</figref>, and is typically 2 to 4 mm more than height H<b>1</b> (18 to 24 mm).

An outer surface <b>58</b> of tubular portion <b>56</b> is formed with top and bottom teeth engagement surfaces <b>60</b> and <b>62</b>, such that top teeth engagement surface <b>60</b> is relatively forward of bottom teeth engagement surface <b>62</b>. This structure facilitates easy and accurate biting of the bite block <b>50</b> by a subject, as it is suited to the jaw morphology of a closed human mouth. Surface <b>58</b> is additionally formed with jaw engagement recesses <b>64</b>, which are formed forwardly of teeth engagement surfaces <b>60</b> and <b>62</b>, respectively.

A top inner surface <b>70</b> of main body portion <b>52</b> is formed with a longitudinal groove <b>72</b> having a transverse surface <b>73</b>, which is adapted to accommodate oral prong <b>22</b> and oral breath directing element <b>26</b> of the oral nasal sampling cannula <b>10</b> (<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>), as described with more detail herein below with reference to <figref idrefs="DRAWINGS">FIG. 4</figref>.

A flexible barrier <b>76</b>, preferably comprised of several flaps <b>78</b>, is disposed within central opening <b>54</b>, thereby substantially closing off the central opening and preventing dilution of exhaled breath by ambient air during sampling. An opening <b>80</b> is preferably maintained within flexible barrier <b>76</b>, thereby ensuring a small part of central opening <b>54</b> remains open in order to enable the subject to inhale external air. The flexible barrier <b>76</b> ensures that a majority of the subject's orally exhaled breath will be directed toward oral prong <b>22</b> (<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) thereby ensuring accurate sampling of the subject's breath. Opening <b>80</b> is preferably placed at a top part of central opening <b>54</b> near the cut-away tip <b>24</b> of oral prong <b>22</b> (<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>), thereby directing exhaled breath toward the oral prong <b>22</b> as it is the only substantial exit.

The flaps <b>78</b> are preferably formed of a plastic material selected to be of suitable thickness to maintain their position when undisturbed, yet bend readily when pushed by an endoscope probe, and thus do not limit the actions of the medical personnel performing the endoscopy. However, the flaps <b>78</b> preferably close back around the endoscope probe, thus maintaining a substantially closed oral cavity volume and allowing most of the exchange of gases to occur close to the opening <b>80</b> of the flexible barrier <b>76</b> which is close to the cut-away tip <b>24</b> of oral prong <b>22</b> (<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) from which capnographic sampling can be performed accurately. Additionally, the flaps <b>78</b> are preferably transparent, thus enabling medical personnel to see into the oral cavity during the endoscopy procedure.

Two attachment surfaces <b>82</b>, each formed with a slit <b>84</b>, extend horizontally outwardly from main body portion <b>52</b>. Slits <b>84</b> are adapted to connect to a band which is placed around the subject's head and is used to maintain the endoscopic bite block <b>50</b> firmly in position during the endoscopy procedure. Preferably, slits <b>84</b> are located above a horizontal centerline of main body portion <b>52</b>, such that the connected band will tend to exert a stronger pull to the top of the main body portion <b>52</b>, thus assisting in overcoming the subject's tendency to tilt the bite block <b>50</b> outward during the endoscopy procedure and in maintaining the bite block <b>50</b> upright in the subject's mouth.

Reference is now made to <figref idrefs="DRAWINGS">FIG. 4</figref>, which is a simplified schematic illustration of the connection between the oral nasal sampling cannula of <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> and the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 2A-3</figref>.

As seen in <figref idrefs="DRAWINGS">FIG. 4</figref>, oral prong <b>22</b> of oral nasal sampling cannula <b>10</b> is accommodated within groove <b>72</b> of bite block <b>50</b>, such that a bottom surface of oral breath directing element <b>26</b> engages transverse surface <b>73</b> of the groove <b>72</b>. It is appreciated that transverse surface <b>73</b> is located below an inner surface of tubular portion <b>56</b> in order to ensure that air exhaled by the subject into tubular portion <b>56</b> will be directed toward groove <b>72</b> and oral prong <b>22</b>.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 5A</figref>, <b>5</b>B, <b>5</b>C, <b>5</b>D, <b>5</b>E, <b>5</b>F and <b>5</b>G, which are pictorial illustrations of various stages of typical use of the endoscopic bite block assembly of <figref idrefs="DRAWINGS">FIGS. 1A-4</figref>.

As seen in <figref idrefs="DRAWINGS">FIG. 5A</figref>, the nasal prongs <b>18</b> of the oral nasal sampling cannula <b>10</b> are placed in the subjects nostrils, preferably before the subject is sedated. Preferably, the exhaled breath collection tube <b>34</b> and the oxygen delivery tube <b>38</b> are placed around the subject's ears, in order to ensure the stability of the oral nasal sampling cannula <b>10</b> on the subject's face. As seen in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 5A</figref>, at this stage the oral breath-directing element <b>26</b> is in its retracted orientation, indicated by the length H<b>3</b>.

Turning to <figref idrefs="DRAWINGS">FIG. 5B</figref>, it is seen that the oral breath directing element <b>26</b> is extended to accommodate the facial dimensions of the subject, revealing part of oral prong <b>22</b>. Preferably, the oral breath-directing element is moved down to a point in which a bottom end thereof is at the height of the top of the bottom lip of the subject, its new length being indicated by H<b>4</b>. This action is preferably preformed by medical personnel, but may alternatively be performed by the subject himself, a family member, or any other person.

<figref idrefs="DRAWINGS">FIG. 5C</figref> illustrates the insertion of bite block <b>50</b> into the mouth of the subject, such that main body portion <b>52</b> engages the outer surface of the subject's lips and the tubular portion <b>56</b> is inside the subject's mouth. A strap, indicated by reference numeral <b>90</b>, is attached to slits <b>84</b> of attachment surfaces <b>82</b> and is placed around the subject's head, thereby securing the bite block <b>50</b> in place. This stage is preferably performed when the subject is sedated, but may alternatively be performed prior thereto.

As seen in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 5C</figref>, the oral breath directing element <b>26</b> and the oral prong <b>22</b> are accommodated in groove <b>72</b>, such that a bottom surface of the oral breath directing element <b>26</b> engages transverse surface <b>73</b> of groove <b>72</b>. Additionally, if oral breath directing element <b>26</b> has been extended more than necessary for the facial features of the subject, the transverse surface <b>73</b> pushes the oral breath-directing element <b>26</b> back, until it is optimally positioned. The lips of the subject, indicated by reference numeral <b>92</b> preferably engage jaw engagement recesses <b>64</b>, and the top and bottom teeth of the subject, indicated by reference numerals <b>94</b> and <b>96</b> engage top and bottom teeth engagement surfaces <b>60</b> and <b>62</b>, respectively.

Turning to <figref idrefs="DRAWINGS">FIG. 5D</figref>, it is seen that air exhaled orally by the subject, indicated by arrows, passes through the bore of tubular portion <b>56</b>, and is directed toward oral breath directing element <b>26</b> and oral prong <b>22</b> by the flaps <b>78</b> of flexible barrier <b>76</b>. Air that is exhaled nasally by the subject passes through nasal prongs <b>18</b>.

<figref idrefs="DRAWINGS">FIG. 5E</figref> illustrates the sedated subject, having the nasal prongs <b>18</b> of the oral nasal sampling cannula <b>10</b> in his nostrils and the endoscopic bite block <b>50</b> placed in his mouth and strapped to his head. Preferably, once the subject is sedated, oxygen is supplied to the nose of the subject via oxygen delivery openings <b>36</b> of oral nasal sampling cannula <b>10</b>, as indicated by arrows in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 5E</figref>. The oxygen is supplied to oxygen delivery openings <b>36</b> via oxygen delivery bore <b>16</b> (<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) and oxygen delivery tube <b>38</b>.

Turning to <figref idrefs="DRAWINGS">FIG. 5F</figref>, it is seen that when the subject is sedated, he tends to move or slump his head, thereby moving oral nasal sampling cannula <b>10</b> relative to bite block <b>50</b>, as indicated by angle a in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 5F</figref>. The feature of the present invention which provides oral nasal sampling cannula <b>10</b> which is physically separated from bite block <b>50</b> and the placement of oral breath directing element <b>26</b> and oral prong <b>22</b> within groove <b>72</b>, ensure that even when the subject moves or slumps his head, the oral prong <b>22</b> and nasal prongs <b>18</b> will be maintained in their respective places, and accurate sampling will continue. Additionally, the placement of oral prong <b>22</b> within groove <b>72</b> provides a counter force to force applied by the subject's tongue to push at least the top portion of the bite block <b>50</b> out of the subject's mouth, thus ensuring accurate placement of the bite block.

As seen in <figref idrefs="DRAWINGS">FIG. 5G</figref>, an endoscope probe <b>98</b> is inserted into the bore of tubular portion <b>56</b> of bite block <b>50</b>, for performing an endoscopy procedure. During the insertion of endoscope probe <b>98</b> and its presence in the subject's mouth and pharynx, flaps <b>78</b> of flexible barrier <b>76</b> bend slightly inward to allow the passage of the endoscope probe <b>98</b>, as seen with particular clarity in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 5G</figref>. However, the central opening <b>54</b> of bite block <b>50</b> remains substantially closed by flaps <b>78</b>, thereby separating the exhaled breath of the subject which is in the bore of tubular portion <b>56</b> from the ambient air.

Additionally, the sampling may continue during the presence of the endoscope probe <b>98</b> in the pharynx of the subject, as the tubular portion <b>56</b> is of a slightly larger diameter than the central opening <b>54</b>, thereby ensuring that medical personnel have the space required for the endoscopy procedure and sampling can take place from the space defined by the difference between heights H<b>2</b> and H<b>1</b> (<figref idrefs="DRAWINGS">FIG. 3</figref>), as indicated by arrows in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 5G</figref>.

It is appreciated that following the endoscopy, the bite block <b>50</b> may be removed from the subject's mouth, preferably by medical personnel. However, the sampling of exhaled breath through nasal prongs <b>18</b> which remain in the subject's nostrils and through oral prong <b>22</b> which remains near the subject's mouth, preferably continues until the subject has awaken from the sedation. This is necessary because the subject's breath must be monitored as long as the subject is sedated.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>, which are simplified pictorial illustrations of an oral nasal sampling cannula forming part of an endoscopic bite block assembly, constructed and operative in accordance with another preferred embodiment of the present invention, in retracted and extended orientations respectively.

<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref> show an oral nasal sampling cannula <b>110</b>, which is adapted for collection of gases, such as carbon dioxide, exhaled by a subject, and for supplying oxygen to the subject.

The oral nasal sampling cannula <b>110</b> comprises a main body portion <b>112</b>, having formed therein an exhaled breath collection bore <b>114</b> and an oxygen delivery bore <b>116</b>. A pair of hollow nasal prongs <b>118</b>, which are adapted for insertion into the nostrils of the subject, is integrally formed with the main body portion <b>112</b>. A hollow oral prong <b>122</b>, which is formed with a limiting rib <b>123</b> and a cut-away tip <b>124</b>, is mounted onto a bottom surface of main body portion <b>112</b>. An oral breath directing element <b>126</b>, which is preferably in the shape of a cut-away tube, is slidably mounted onto oral prong <b>122</b> by a mounting portion <b>128</b>, and positioning of the oral breath directing element <b>126</b> is limited by the limiting rib <b>123</b> of oral prong <b>122</b>.

A channel formed in oral prong <b>122</b> is in fluid flow connection with channels formed in nasal prongs <b>118</b>, thereby forming a single junction <b>132</b>. Single junction <b>132</b> is in fluid flow communication with exhaled breath collection bore <b>114</b>, which in turn is in fluid flow communication with an exhaled breath collection tube <b>134</b>, which is adapted to be connected to a breath test analyzer or a capnograph (not shown), such as Microcap® which is commercially available from Oridion Medical LTD. of Jerusalem, Israel.

Main body portion <b>112</b> is formed with oxygen delivery openings <b>136</b>, which are in fluid flow communication with oxygen delivery bore <b>116</b>, which in turn is in fluid flow communication with an oxygen delivery tube <b>138</b>. Alternatively, at least one nasal oxygen delivery prong, which is adapted to be inserted into the nostril of the subject, may be used instead of oxygen delivery openings <b>136</b>. Oxygen delivery tube <b>138</b> is preferably formed with a T-element <b>140</b>, connecting the oxygen delivery tube <b>138</b> to an oral oxygen delivery tube <b>142</b>. Oxygen delivery tube <b>138</b> is adapted to be connected to a source of oxygen (not shown). Oral oxygen delivery tube <b>142</b> is preferably normally closed by a valve element <b>144</b>. Typically, the valve is a luer type valve.

Oxygen delivery tube <b>138</b> and exhaled breath collection tube <b>134</b> may optionally be placed around the ears of the subject, thereby stabilizing the oral nasal sampling cannula <b>110</b> on the subject's face, such that any movement of the subject will have negligible effect on the placement of the oral nasal sampling cannula <b>110</b>.

It is appreciated that oral breath directing element <b>126</b> may be in a retracted orientation as shown in <figref idrefs="DRAWINGS">FIG. 6A</figref>, or in an extended orientation as shown in <figref idrefs="DRAWINGS">FIG. 6B</figref>, thereby allowing the oral nasal sampling cannula <b>110</b> to be suited to the facial dimensions of the subject, resulting in more efficient collection of exhaled breath.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 7A and 7B</figref>, which are front-view and rear-view simplified pictorial illustrations of an endoscopic bite block forming part of an endoscopic bite block assembly constructed and operative in accordance with a preferred embodiment of the present invention and to <figref idrefs="DRAWINGS">FIG. 8</figref>, which is a simplified sectional pictorial illustration thereof.

<figref idrefs="DRAWINGS">FIGS. 7A</figref>, <b>7</b>B and <b>8</b> show an endoscopic bite block <b>150</b>, which is adapted to be inserted into the mouth of a subject while the subject is sedated, to ensure that the mouth of the subject is maintained open during the endoscopy process and that the subject does not interfere with the process by biting on the medical instruments used.

The endoscopic bite block <b>150</b> includes a main body portion <b>152</b>, having formed therein a central opening <b>154</b>. A hollow tubular portion <b>156</b> extends distally from main body portion <b>152</b>, such that the opening of tubular portion <b>156</b> is an extension of central opening <b>154</b>. Central opening <b>154</b> is of a first height, indicated by H<b>1</b> in <figref idrefs="DRAWINGS">FIG. 8</figref>, which is typically 16 to 20 mm in bite blocks for adult use, which is the height required by medical personnel for performing an endoscopy. In order to ensure that during breath sampling, oral prong <b>122</b> of oral nasal sampling cannula <b>110</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>) does not interfere with the space required by medical personnel for performing the endoscopy procedure, the height of tubular portion <b>156</b> is greater than the height H<b>1</b> of central opening <b>154</b> as indicated by H<b>2</b> in <figref idrefs="DRAWINGS">FIG. 8</figref>, and is typically 2 to 4 mm more than height H<b>1</b> (18 to 24 mm).

An outer surface <b>158</b> of tubular portion <b>156</b> is formed with top and bottom teeth engagement surfaces <b>160</b> and <b>162</b>, such that top teeth engagement surface <b>160</b> is relatively forward of bottom teeth engagement surface <b>162</b>. This structure facilitates easy and accurate biting of the bite block <b>150</b> by a subject, as it is suited to the jaw morphology of a closed human mouth. Surface <b>158</b> is additionally formed with jaw engagement recesses <b>164</b>, which are formed forwardly of teeth engagement surfaces <b>160</b> and <b>162</b>, respectively.

A top inner surface <b>170</b> of main body portion <b>152</b> is formed with a longitudinal groove <b>172</b> having a transverse surface <b>173</b>, which is adapted to accommodate oral prong <b>122</b> and oral breath directing element <b>126</b> of the oral nasal sampling cannula <b>110</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>), as described with more detail hereinbelow with reference to <figref idrefs="DRAWINGS">FIG. 9</figref>.

A tubular portion <b>174</b> is formed on a side of outer surface <b>158</b> of tubular portion <b>156</b>. Tubular portion <b>174</b> is adapted to threadably engage oral oxygen delivery tube <b>142</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>), thereby opening valve <b>144</b> to the passage of gases and thus supplying oxygen directly to the oral cavity of the subject. Preferably, tubular portion <b>174</b> includes a luer portion corresponding to luer valve element <b>144</b>. It is appreciated that tubular portion <b>174</b> is formed on outer surface <b>158</b> of tubular portion <b>156</b>, in order to ensure that the oral oxygen delivery does not interfere with the procedure performed by the medical personnel and so that the oxygen flow does not directly interfere with the CO2 sampling.

A flexible barrier <b>176</b>, preferably comprised of several flaps <b>178</b>, is disposed within central opening <b>154</b>, thereby substantially closing off the central opening and preventing dilution of exhaled breath by ambient air during sampling. An opening <b>180</b> is preferably maintained within flexible barrier <b>176</b>, thereby ensuring a small part of central opening <b>154</b> to remain open in order to enable the subject to inhale external air. The flexible barrier <b>176</b> ensures that a majority of the subject's orally exhaled breath will be directed toward oral prong <b>122</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>) thereby ensuring accurate sampling of the subject's breath. Opening <b>180</b> is preferably placed at a top part of central opening <b>154</b> near the cut-away tip <b>124</b> of oral prong <b>122</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>), thereby directing exhaled breath toward the oral prong <b>122</b> as it is the only substantial exit.

The flaps <b>178</b> are preferably formed of a plastic material selected to be of suitable thickness to maintain their position when undisturbed, yet bend readily when pushed by an endoscope probe, and thus do not limit the actions of the medical personnel performing the endoscopy. However, the flaps <b>178</b> preferably close back around the endoscope probe, thus maintaining a substantially closed oral cavity volume, and allowing most of the exchange of gases to occur close to the opening <b>180</b> of the flexible barrier <b>176</b>, which opening is close to the cut-away tip <b>124</b> of oral prong <b>122</b> from which capnographic sampling can be performed accurately. Additionally, the flaps <b>178</b> are preferably transparent, thus enabling medical personnel to see into the oral cavity during the endoscopy procedure.

Two attachment surfaces <b>182</b>, each formed with a slit <b>184</b>, extend horizontally outwardly from main body portion <b>152</b>. Slits <b>184</b> are adapted to connect to a band which is place around the subject's head and is used to maintain the endoscopic bite block <b>150</b> firmly in position during the endoscopy procedure. Preferably, slits <b>184</b> are located above a horizontal centerline of main body portion <b>152</b>, such that the connected band will tend to exert a stronger pull to the top of the main body portion <b>152</b>, thus assisting in overcoming the subject's tendency to tilt the bite block <b>150</b> outward during the endoscopy procedure and in maintaining the bite block <b>150</b> upright in the subject's mouth.

Reference is now made to <figref idrefs="DRAWINGS">FIG. 9</figref>, which is a simplified schematic illustration of the connection between the oral nasal sampling cannula of <figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref> and the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 7A-8</figref>.

As seen in <figref idrefs="DRAWINGS">FIG. 9</figref>, oral prong <b>122</b> of oral nasal sampling cannula <b>110</b> is accommodated within groove <b>172</b> of bite block <b>150</b>, such that a bottom surface of oral breath directing element <b>126</b> engages transverse surface <b>173</b> of the groove <b>172</b>. It is appreciated that transverse surface <b>173</b> is located below an inner surface of tubular portion <b>156</b> in order to ensure that air exhaled by the subject into tubular portion <b>156</b> will be directed toward groove <b>172</b> and oral prong <b>122</b>.

Additionally, valve <b>144</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>) of oral oxygen delivery tube <b>142</b> is accommodated in tubular portion <b>174</b> of endoscopic bite block <b>150</b>, thereby opening the valve element and forming a fluid flow engagement between oxygen delivery tube <b>138</b> and tubular portion <b>174</b> of endoscopic bite block <b>150</b>, which is in fluid flow engagement with the oral cavity of the subject.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 10A</figref>, <b>10</b>B, <b>10</b>C, <b>10</b>D, <b>10</b>E, <b>10</b>F and <b>10</b>G, which are pictorial illustrations of various stages of typical use of the endoscopic bite block assembly of <figref idrefs="DRAWINGS">FIGS. 6A-9</figref>.

As seen in <figref idrefs="DRAWINGS">FIG. 10A</figref>, the nasal prongs <b>118</b> of the oral nasal sampling cannula <b>110</b> are placed in the subjects nostrils, preferably before the subject is sedated. Preferably, the exhaled breath collection tube <b>134</b> and the oxygen delivery tube <b>138</b> are placed around the subject's ears, in order to ensure the stability of the oral nasal sampling cannula <b>110</b> on the subject's face. As seen in the enlarged portion of FIG. <b>10</b>A, at this stage the oral breath-directing element <b>126</b> is in its retracted orientation, indicated by the length H<b>3</b>. At this stage, oral oxygen delivery tube <b>142</b> is not connected to the bite block <b>150</b> (<figref idrefs="DRAWINGS">FIGS. 7A-8</figref>).

Turning to <figref idrefs="DRAWINGS">FIG. 10B</figref>, it is seen that the oral breath directing element <b>126</b> is extended to accommodate the facial dimensions of the subject, revealing part of oral prong <b>122</b>. Preferably, the oral breath-directing element is moved down to a point in which a bottom end thereof is at the height of the top of the bottom lip of the subject, its new length being indicated by H<b>4</b>. This action is preferably preformed by medical personnel, but may alternatively be performed by the subject himself, a family member, or any other person.

<figref idrefs="DRAWINGS">FIG. 10C</figref> illustrates the insertion of bite block <b>150</b> into the mouth of the subject, such that main body portion <b>152</b> engages the outer surface of the subject's lips and the tubular portion <b>156</b> (<figref idrefs="DRAWINGS">FIGS. 7A-8</figref>) is inside the subject's mouth. Additionally, valve <b>144</b> of oral oxygen delivery tube <b>142</b> is inserted, preferably by medical personnel, into tubular portion <b>174</b> of endoscopic bite block <b>150</b>, as indicated by an arrow in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 10C</figref>, thereby opening the valve and allowing passage of fluids from the oral oxygen delivery tube <b>142</b> into the oral cavity of the subject.

A strap, indicated by reference numeral <b>190</b>, is attached to slits <b>184</b> of attachment surfaces <b>182</b> and is placed around the subject's head, thereby securing the bite block <b>150</b> in place. This stage is preferably performed when the subject is sedated, but may alternatively be performed prior thereto.

Turning to <figref idrefs="DRAWINGS">FIG. 10D</figref>, it is seen that air exhaled orally by the subject, indicated by arrows, passes through the bore of tubular portion <b>156</b>, and is directed toward oral breath directing element <b>126</b> and oral prong <b>122</b> by the flaps <b>178</b> of flexible barrier <b>176</b>. Air that is exhaled nasally by the subject passes through nasal prongs <b>118</b>.

<figref idrefs="DRAWINGS">FIG. 10D</figref> illustrates the oral breath directing element <b>126</b> and the oral prong <b>122</b> being accommodated in groove <b>172</b>, such that a bottom surface of the oral breath directing element <b>126</b> engages transverse surface <b>173</b> of groove <b>172</b>. Additionally, if oral breath directing element <b>126</b> has been extended more than necessary for the facial features of the subject, the transverse surface <b>173</b> pushes the oral breath-directing element <b>126</b> back until it is optimally positioned. The lips of the subject, indicated by reference numeral <b>192</b> preferably engage jaw engagement recesses <b>164</b>, and the top and bottom teeth of the subject, indicated by reference numerals <b>194</b> and <b>196</b> engage top and bottom teeth engagement surfaces <b>160</b> and <b>162</b>, respectively.

<figref idrefs="DRAWINGS">FIG. 10E</figref> illustrates the sedated subject, having the nasal prongs <b>118</b> of the oral nasal sampling cannula <b>110</b> in his nostrils and the endoscopic bite block <b>150</b> placed in his mouth and strapped to his head. Preferably, once the subject is sedated, oxygen is supplied to the nose of the subject via oxygen delivery openings <b>136</b> of oral nasal sampling cannula <b>110</b>, and to the mouth of the subject via oral oxygen delivery tube <b>142</b> and tubular portion <b>174</b>, as indicated by arrows. The oxygen is supplied to the oxygen delivery openings <b>136</b> via oxygen delivery bore <b>116</b> (<figref idrefs="DRAWINGS">FIGS. 6A and 6B</figref>) and to oral oxygen delivery tube <b>142</b> via oxygen delivery tube <b>138</b> and T-element <b>140</b>.

Turning to <figref idrefs="DRAWINGS">FIG. 10F</figref>, it is seen that when the subject is sedated, he tends to move or slump his head, thereby moving oral nasal sampling cannula <b>110</b> relative to bite block <b>150</b>, as indicated by angle a in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 10F</figref>. The feature of the present invention which provides oral nasal sampling cannula <b>110</b> which is physically separated from bite block <b>150</b> and the placement of oral breath directing element <b>126</b> and oral prong <b>122</b> within groove <b>172</b>, ensure that even when the subject moves or slumps his head, the oral prong <b>122</b> and nasal prongs <b>118</b> will be maintained in their respective places, and accurate sampling will continue. Additionally, the placement of oral prong <b>122</b> within groove <b>172</b> provides a counter force to force applied by the subject's tongue to push at least the top portion of the bite block <b>150</b> out of the subject's mouth, thus ensuring accurate placement of the bite block.

As seen in <figref idrefs="DRAWINGS">FIG. 10G</figref>, an endoscope probe <b>198</b> is inserted into the bore of tubular portion <b>156</b> of bite block <b>150</b>, for performing the endoscopy procedure. During the insertion of endoscope probe <b>198</b> and its presence in the subject's mouth and pharynx, flaps <b>178</b> of flexible barrier <b>176</b> bend slightly inward to allow the passage of the endoscope probe <b>198</b>, as seen with particular clarity in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 10G</figref>. However, the central opening <b>154</b> of bite block <b>150</b> remains substantially closed by flaps <b>178</b>, thereby separating the exhaled breath of the subject which is in bore of tubular portion <b>156</b> from the ambient air.

Additionally, the sampling may continue during the presence of the endoscope probe <b>198</b> in the pharynx of the subject, as the tubular portion <b>156</b> is of a slightly larger diameter than the central opening <b>154</b>, thereby ensuring that medical personnel have the space defined by the difference between heights H<b>2</b> and H<b>1</b> (<figref idrefs="DRAWINGS">FIG. 8</figref>), as indicated by arrows in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 10G</figref>.

It is appreciated that following the endoscopy, the bite block <b>150</b> may be removed from the subject's mouth, preferably by medical personnel. Prior to this stage, the valve <b>144</b> of oral oxygen delivery tube <b>142</b> is removed from tubular portion <b>174</b> thereby closing the valve and thus fully decoupling the oral nasal sampling cannula <b>110</b> from the endoscopic bite block <b>150</b>. However, the sampling of exhaled breath through nasal prongs <b>118</b> which remain in the subject's nostrils and through oral prong <b>122</b> which remains near the subject's mouth, preferably continues until the subject has awaken from the sedation. This is necessary because the subject's breath must be monitored as long as the subject is sedated.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>, which are simplified pictorial illustrations of an oral nasal sampling cannula forming part of an endoscopic bite block assembly, constructed and operative in accordance with yet another preferred embodiment of the present invention, in retracted and extended orientations respectively.

<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref> show an oral nasal sampling cannula <b>210</b>, which is adapted for collection of gases, such as carbon dioxide, exhaled by a subject, and for supplying oxygen to the subject.

The oral nasal sampling cannula <b>210</b> comprises a main body portion <b>212</b>, having formed therein an exhaled breath collection bore <b>214</b> and an oxygen delivery bore <b>216</b>. A pair of hollow nasal prongs <b>218</b>, which are adapted for insertion into the nostrils of the subject, is integrally formed with the main body portion <b>212</b>. A hollow oral prong <b>222</b>, which is formed with a limiting rib <b>223</b> and a cut-away tip <b>224</b>, is mounted onto a bottom surface of main body portion <b>212</b>. An oral breath directing element <b>226</b>, which is preferably in the shape of a cut-away tube, is slidably mounted onto oral prong <b>222</b> by a mounting portion <b>228</b>, and positioning of the oral breath directing element <b>226</b> is limited by the limiting rib <b>223</b> of oral prong <b>222</b>.

A channel formed in oral prong <b>222</b> is in fluid flow connection with channels formed in nasal prongs <b>218</b>, thereby forming a single junction <b>232</b>. Single junction <b>232</b> is in fluid flow communication with exhaled breath collection bore <b>214</b>, which in turn is in fluid flow communication with an exhaled breath collection tube <b>234</b>, which is adapted to be connected to a breath test analyzer or a capnograph (not shown), such as Microcap® which is commercially available from Oridion Medical LTD. of Jerusalem, Israel.

Main body portion <b>212</b> is formed with oxygen delivery openings <b>236</b>, which are in fluid flow communication with oxygen delivery bore <b>216</b>, which in turn is in fluid flow communication with an oxygen delivery tube <b>238</b>. Alternatively, at least one nasal oxygen delivery prong, adapted for insertion into the subject's nostril, may be used instead of oxygen delivery openings <b>236</b>. Oxygen delivery tube <b>238</b> is preferably formed with a T-element <b>240</b>, preferably terminating at an end thereof in a normally closed valve element <b>244</b>, which is preferably a luer valve. Oxygen delivery tube <b>238</b> is adapted to be connected to a source of oxygen (not shown).

Oxygen delivery tube <b>238</b> and exhaled breath collection tube <b>234</b> may optionally be placed around the ears of the subject, thereby stabilizing the oral nasal sampling cannula <b>210</b> on the subject's face, such that any movement of the subject will have negligible effect on the placement of the oral nasal sampling cannula <b>210</b>.

It is appreciated that oral breath directing element <b>226</b> may be in a retracted orientation as shown in <figref idrefs="DRAWINGS">FIG. 11A</figref>, or in an extended orientation as shown in <figref idrefs="DRAWINGS">FIG. 11B</figref>, thereby allowing the oral nasal sampling cannula <b>210</b> to be suited to the facial dimensions of the subject, resulting in more efficient collection of exhaled breath.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 12A and 12B</figref>, which are front-view and rear-view simplified pictorial illustrations of an endoscopic bite block forming part of an endoscopic bite block assembly constructed and operative in accordance with yet another preferred embodiment of the present invention and to <figref idrefs="DRAWINGS">FIG. 13</figref>, which is a simplified sectional pictorial illustration thereof.

<figref idrefs="DRAWINGS">FIGS. 12A</figref>, <b>12</b>B and <b>13</b> show an endoscopic bite block <b>250</b>, which is adapted to be inserted into the mouth of a subject while the subject is sedated, to ensure that the mouth of the subject is maintained open during the endoscopy process, and that the subject does not interfere with the process by biting on medical instruments used.

The endoscopic bite block <b>250</b> includes a main body portion <b>252</b>, having formed therein a central opening <b>254</b>. A hollow tubular portion <b>256</b> extends distally from main body portion <b>252</b>, such that the opening of tubular portion <b>256</b> is an extension of central opening <b>254</b>. Central opening <b>254</b> is of a first height, indicated by H<b>1</b> in <figref idrefs="DRAWINGS">FIG. 13</figref>, which is typically 16 to 20 mm in bite blocks for adult use, which is the height required by medical personnel for performing an endoscopy. In order to ensure that during breath sampling, oral prong <b>222</b> of oral nasal sampling cannula <b>210</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>) does not interfere with the space required by medical personnel for performing the endoscopy procedure, the height of tubular portion <b>256</b> is greater than the height H<b>1</b> of central opening <b>254</b> as indicated by H<b>2</b> in <figref idrefs="DRAWINGS">FIG. 13</figref>, and is typically 2 to 4 mm more than height H<b>1</b> (18 to 24 mm).

An outer surface <b>258</b> of tubular portion <b>256</b> is formed with top and bottom teeth engagement surfaces <b>260</b> and <b>262</b>, such that top teeth engagement surface <b>260</b> is relatively forward of bottom teeth engagement surface <b>262</b>. This structure facilitates easy and accurate biting of the bite block <b>250</b> by a subject, as it is suited to the jaw morphology of a closed human mouth. Surface <b>258</b> is additionally formed with jaw engagement recesses <b>264</b>, which are formed forwardly of teeth engagement surfaces <b>260</b> and <b>262</b>, respectively.

A top inner surface <b>270</b> of main body portion <b>252</b> is formed with a longitudinal groove <b>272</b> having a transverse surface <b>273</b>, which is adapted to accommodate oral prong <b>222</b> and oral breath directing element <b>226</b> of the oral nasal sampling cannula <b>210</b> (<figref idrefs="DRAWINGS">FIGS. 12A and 12B</figref>), as described with more detail hereinbelow with reference to <figref idrefs="DRAWINGS">FIG. 14</figref>.

A tubular portion <b>274</b> is formed on a side of outer surface <b>258</b> of tubular portion <b>256</b>. Extending out of tubular portion <b>274</b> is an oral oxygen delivery tube <b>275</b> including a tip <b>276</b>, which is adapted to engage valve <b>244</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>), thereby supplying oxygen directly to the oral cavity of the subject. Preferably, tip <b>276</b> comprises a luer corresponding to luer valve <b>244</b>. It is appreciated that tubular portion <b>274</b> is formed on outer surface <b>258</b> of tubular portion <b>256</b>, in order to ensure that the oral oxygen delivery does not interfere with the procedure performed by the medical personnel.

A flexible barrier <b>277</b>, preferably comprised of several flaps <b>278</b>, is disposed within central opening <b>254</b>, thereby substantially closing off the central opening and preventing dilution of exhaled breath by ambient air during sampling. An opening <b>280</b> is preferably maintained within flexible barrier <b>277</b>, thereby ensuring a small part of central opening <b>254</b> remains open in order to enable the subject to inhale external air. The flexible barrier <b>277</b> ensures that a majority of the subject's orally exhaled breath will be directed toward oral prong <b>222</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>) thereby ensuring accurate sampling of the subject's breath. Opening <b>280</b> is preferably placed at a top part of central opening <b>254</b> near the cut-away tip <b>224</b> of oral prong <b>222</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>), thereby directing and amplifying exhaled breath toward the oral prong <b>222</b> as it is the only substantial exit.

The flaps <b>278</b> are preferably formed of a plastic material selected to be of suitable thickness to maintain their position when undisturbed, yet bend readily when pushed by an endoscope probe, and thus do not limit the actions of the medical personnel performing the endoscopy. However, the flaps <b>278</b> preferably close back around the endoscope probe, thus maintaining a substantially closed oral cavity volume, and allowing most of the exchange of gases to occur close to the opening <b>280</b> of flexible barrier <b>277</b>, which opening is close to the cut-away tip <b>224</b> of oral prong <b>222</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>) from which capnographic sampling can be performed accurately.

Additionally, the flaps <b>278</b> are preferably transparent, thus enabling medical personnel to see into the oral cavity during the endoscopy procedure.

Two attachment surfaces <b>282</b>, each formed with a slit <b>284</b>, extend horizontally outwardly from main body portion <b>252</b>. Slits <b>284</b> are adapted to connect to a band which is placed around the subject's head and is used to maintain the endoscopic bite block <b>250</b> firmly in position during the endoscopy procedure. Preferably, slits <b>284</b> are located above a horizontal centerline of main body portion <b>252</b>, such that the connected band will tend to exert a stronger pull to the top of the main body portion <b>252</b>, thus assisting in overcoming the subject's tendency to tilt the bite block <b>250</b> outward during the endoscopy procedure and in maintaining the bite block <b>250</b> upright in the subject's mouth.

Reference is now made to <figref idrefs="DRAWINGS">FIG. 14</figref>, which is a simplified schematic illustration of the connection between the oral nasal sampling cannula of <figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref> and the endoscopic bite block of <figref idrefs="DRAWINGS">FIGS. 12A-13</figref>.

As seen in <figref idrefs="DRAWINGS">FIG. 14</figref>, oral prong <b>222</b> of oral nasal sampling cannula <b>210</b> is accommodated within groove <b>272</b> of bite block <b>250</b>, such that a bottom surface of oral breath directing element <b>226</b> engages transverse surface <b>273</b> of the groove <b>272</b>. It is appreciated that transverse surface <b>273</b> is located below an inner surface of tubular portion <b>256</b> in order to ensure that air exhaled by the subject into tubular portion <b>256</b> will be directed toward groove <b>272</b> and oral prong <b>222</b>.

Additionally, tip <b>276</b> of oral oxygen delivery tube <b>275</b> engages valve <b>244</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>) of T-element <b>240</b> of oral nasal sampling cannula <b>210</b>, thereby opening the valve <b>244</b> and forming a fluid flow engagement between oxygen delivery tube <b>238</b> and tubular portion <b>274</b> of endoscopic bite block <b>250</b>, which is in fluid flow engagement with the oral cavity of the subject.

Reference is now made to <figref idrefs="DRAWINGS">FIGS. 15A</figref>, <b>15</b>B, <b>15</b>C, <b>15</b>D, <b>15</b>E, <b>15</b>F and <b>15</b>G, which are pictorial illustrations of various stages of typical use of the endoscopic bite block assembly of <figref idrefs="DRAWINGS">FIGS. 11A-14</figref>.

As seen in <figref idrefs="DRAWINGS">FIG. 15A</figref>, the nasal prongs <b>218</b> of the oral nasal sampling cannula <b>210</b> are placed in the subjects nostrils, preferably before the subject is sedated. Preferably, the exhaled breath collection tube <b>234</b> and the oxygen delivery tube <b>238</b> are placed around the subject's ears, in order to ensure the stability of the oral nasal sampling cannula <b>210</b> on the subject's face. As seen in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 15A</figref>, at this stage the oral breath-directing element <b>226</b> is in its retracted orientation, indicated by the length H<b>3</b>.

At this stage, oral oxygen delivery tube <b>275</b> (<figref idrefs="DRAWINGS">FIGS. 12A-13</figref>) is not connected to the T-element <b>240</b> of oral nasal sampling cannula <b>210</b>. However, even if oxygen is supplied to oral nasal sampling cannula <b>210</b> via oxygen delivery tube <b>238</b>, there is no oxygen leakage, as the T-element <b>240</b> is sealed by valve <b>244</b>.

Turning to <figref idrefs="DRAWINGS">FIG. 15B</figref> it is seen that the oral breath directing element <b>226</b> is extended to accommodate the facial dimensions of the subject, revealing part of oral prong <b>222</b>. Preferably, the oral breath-directing element <b>226</b> is moved down to a point in which a bottom end thereof is at the height of the top of the bottom lip of the subject, its new length being indicated by H<b>4</b>. This action is preferably preformed by medical personnel, but may alternatively be performed by the subject himself, a family member, or any other person.

<figref idrefs="DRAWINGS">FIG. 15C</figref> illustrates the insertion of bite block <b>250</b> into the mouth of the subject, such that main body portion <b>252</b> engages the outer surface of the subject's lips and the tubular portion <b>256</b> is inside the subject's mouth. Additionally, tip <b>276</b> of oral oxygen delivery tube <b>275</b> is inserted, preferably by medical personnel, into valve <b>244</b> of T-element <b>240</b> of oral nasal sampling cannula <b>210</b>, as indicated by an arrow in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 15C</figref>, thereby opening the valve <b>244</b>.

A strap, indicated by reference numeral <b>290</b>, is attached to slits <b>284</b> of attachment surfaces <b>282</b> and is placed around the subject's head, thereby securing the bite block <b>250</b> in place. This stage is preferably performed when the subject is sedated, but may alternatively be performed prior thereto.

Turning to <figref idrefs="DRAWINGS">FIG. 15D</figref>, it is seen that air exhaled orally by the subject, indicated by arrows, passes through the bore of tubular portion <b>256</b>, and is directed toward oral breath directing element <b>226</b> and oral prong <b>222</b> by the flaps <b>278</b> of flexible barrier <b>277</b>. Air that is exhaled nasally by the subject passes through nasal prongs <b>218</b>.

<figref idrefs="DRAWINGS">FIG. 15D</figref> illustrates the oral breath directing element <b>226</b> and the oral prong <b>222</b> being accommodated in groove <b>272</b>, such that a bottom surface of the oral breath directing element <b>226</b> engages transverse surface <b>273</b> of groove <b>272</b>. Additionally, if oral breath directing element <b>226</b> has been extended more than necessary for the facial features of the subject, the transverse surface <b>273</b> pushes the oral breath-directing element <b>226</b> back until it is optimally positioned. The lips of the subject, indicated by reference numeral <b>292</b> preferably engage jaw engagement recesses <b>264</b>, and the top and bottom teeth of the subject, indicated by reference numerals <b>294</b> and <b>296</b> engage top and bottom teeth engagement surfaces <b>260</b> and <b>262</b>, respectively.

<figref idrefs="DRAWINGS">FIG. 15E</figref> illustrates the sedated subject, having the nasal prongs <b>218</b> of the oral nasal sampling cannula <b>210</b> in his nostrils and the endoscopic bite block <b>250</b> placed in his mouth and strapped to his head. Preferably, once the subject is sedated, oxygen is supplied to the nose of the subject via oxygen delivery openings <b>236</b> of oral nasal sampling cannula <b>210</b>, and to the mouth of the subject via oral oxygen delivery tube <b>275</b> and tubular portion <b>274</b>, as indicated by arrows. The oxygen is supplied to the oxygen delivery openings <b>236</b> via oxygen delivery bore <b>216</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>) and to oral oxygen delivery tube <b>275</b> via oxygen delivery tube <b>238</b> and T-element <b>240</b>.

Turning to <figref idrefs="DRAWINGS">FIG. 15F</figref>, it is seen that when the subject is sedated, he tends to move or slump his head, thereby moving oral nasal sampling cannula <b>210</b> relative to bite block <b>250</b>, as indicated by angle a in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 15F</figref>. The feature of the present invention which provides oral nasal sampling cannula <b>210</b> which is physically separated from bite block <b>250</b> and the placement of oral breath directing element <b>226</b> and oral prong <b>222</b> within groove <b>272</b>, ensure that even when the subject moves or slumps his head, the oral prong <b>222</b> and nasal prongs <b>218</b> will be maintained in their respective places, and accurate sampling will continue. Additionally, the placement of oral prong <b>222</b> within groove <b>272</b> provides a counter force to force applied by the subject's tongue to push at least the top portion of the bite block <b>250</b> out of the subject's mouth, thus ensuring accurate placement of the bite block.

As seen in <figref idrefs="DRAWINGS">FIG. 15G</figref>, an endoscope probe <b>298</b> is inserted into the bore of tubular portion <b>256</b> of bite block <b>250</b>, for performing the endoscopy procedure. During the insertion of endoscope probe <b>298</b> and its presence in the subject's mouth and pharynx, flaps <b>278</b> of flexible barrier <b>277</b> bend slightly inward to allow the passage of the endoscope probe <b>298</b>, as seen with particular clarity in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 15G</figref>. However, the central opening <b>254</b> of bite block <b>250</b> remains substantially closed by flaps <b>278</b>, thereby separating the exhaled breath of the subject which is in the bore of tubular portion <b>256</b> from the ambient air.

Additionally, the sampling may continue during the presence of the endoscope probe <b>298</b> in the pharynx of the subject, as the tubular portion <b>256</b> is of a slightly larger diameter than the central opening <b>254</b>, thereby ensuring that medical personnel have the space defined by the difference between heights H<b>2</b> and H<b>1</b> (<figref idrefs="DRAWINGS">FIG. 13</figref>), as indicated by arrows in the enlarged portion of <figref idrefs="DRAWINGS">FIG. 15G</figref>.

It is appreciated that following the endoscopy the bite block <b>250</b> may be removed from the subject's mouth, preferably by medical personnel. Prior to this stage, the tip <b>276</b> of oral oxygen delivery tube <b>275</b> is removed from valve <b>244</b> (<figref idrefs="DRAWINGS">FIGS. 11A and 11B</figref>) of T-element <b>240</b>, thereby closing the valve and fully decoupling the oral nasal sampling cannula <b>210</b> from the endoscopic bite block <b>250</b>. However, the sampling of exhaled breath through nasal prongs <b>218</b> which remain in the subject's nostrils and through oral prong <b>222</b> which remains near the subject's mouth, preferably continues until the subject has awaken from the sedation. This is necessary because the subject's breath must be monitored as long as the subject is sedated.

It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.